Methods and apparatuses, called driver assistance systems, are described in the existing art in a variety of manifestations. Examples of such driver assistance systems are adaptive cruise control (ACC) systems, which adapt the vehicle's speed to maintain a separation from a preceding vehicle; lane departure warning systems, which warn the driver upon departure from the lane; systems for monitoring the blind-spot, which warn the driver about objects in the “blind spot” of the driver's field of view when changing lanes, etc. An example of an adaptive cruise control system is shown in German Patent Application No. 101 18 295, and an example of a lane departure warning system in European Patent Application No. 1 074 430. In lane departure warning systems in particular, but also in some ACC embodiments, the system checks whether the vehicle is departing, or about to depart, from the lane delimited, for example, by road edge markings. A considerable functional improvement would be achieved here if a distinction could be made between an intentional and unintentional lane change, i.e. for example between a lane change for passing purposes and a lane change due to inattention by the driver.